Removed all dependencies on UF types (fixes Eclipse JDT APT bug)

See comments in https://bugs.eclipse.org/bugs/show_bug.cgi?id=280542 for details
Removed slf4j because it sometimes breaks under eclipse JDT. Now all logging is done via the official Messager API.
Cleaned up some usages of GenerationException and added a note saying not to use it for new stuff
Disabled logging inside Freemarker; its attempt to initialize inside JDT was causing ExceptionInInitializerError
maven-shade-plugin version 2.2 works under Maven 3 (inherited managed version 2.0 does not)
Adding Errai security as a core dependency; now relying on it for local user cache behaviour
Updated for latest Errai Security API changes
Updated to latest Errai API
(WIP) Removed uberfire-security-server and cleaned up the resulting compile issues.

Right now, all non-test code compiles, but the tests don't compile and the showcase app doesn't deploy.
Further commits will clean these loose ends up.
All security filter tests that still make sense are passing!
Remove uberfire-security-picketlink (classes moved to errai-security-picketlink).